1. Field of the Invention
The present invention relates to the field of turbomachines, and in particular to a rotor for a compressor.
2. Brief Description of the Related Art
Rotors for high-pressure compressors, as are used in particular in gas turbines, generally have a multistage blade system, which includes blade rims which are arranged one behind the other in the axial direction. Each blade rim contains a large number of rotor blades, which are arranged on and attached to the circumference of the rotor. Each of the rotor blades is seated by means of a blade root in a circumferential groove, which is in the form of a recess in the rotor. One such rotor is known, for example, from the document DE-A1-196 15 549.
FIG. 1 also shows how a single rotor blade is mounted in a rotor according to the prior art: the rotor blade 15 has a blade section 12 which projects radially outwards and a blade root 16, which are separated from one another by a platform 18. The rotor blade 15 is mounted in the rotor 10 by means of the blade root 16. A circumferential groove, in the form of a recess 11 which has a recess depth T, is provided for attachment of the rotor blades. Shoulders 14 with a shoulder depth A are formed on the side walls within the recess 11. The blade root 16 has a widening lower part 17 with a cross-sectional contour in the form of an inverted “T”, by means of which it engages behind the shoulders 14 of the recess 11. The centrifugal force which acts on the rotor blade 15 during rotation of the rotor 10 is in this case transmitted via contact surfaces 13 to the shoulders 14 of the recess 11.
In order to avoid the recesses 11 for the rotor blades weakening the mechanical strength of the rotor any more than necessary, the recesses 11 in the prior art have a minimum recess depth T=Tmin,1. This minimum recess depth Tmin,1 allows the shoulder 14 to have a shoulder depth A which is just sufficient to allow sufficient initial strength of the rotor 10 in the area of the shoulders 14 in the prevailing extreme operating conditions (high rotation speeds, temperatures up to 500° C. ) and with the characteristics of the chosen rotor material.
Now, however, it has been found in practice that the use of a recess with the minimum recess depth Tmin,1 can lead to the rotor 10 being stressed beyond the permissible strength limits in the area of the recess 11, and this can lead to a reduction in the rotor life.